17, 12, 14, 18
The reference text for this subject. Its most transferable contributions are the staging rule (arterial signal lost equals threatened, both signals lost equals non-salvageable), the six-step conservative ladder that precedes any procedure, and the observation that Doppler velocity degrades as ECMO flow rises - the leg equivalent of the pulse-oximetry failure in Chapter 16.
Not applicable
DOI 10.1186/s13054-019-2541-3
Not applicable - synthesis of incidence, risk factors, prevention, monitoring and treatment of limb ischaemia
Narrative review, not systematic. Data described by the authors themselves as highly fragmentary with no clear-cut recommendations. The incidence range spans a factor of seven because there is no agreed definition. Two internal number problems were found on audit and are flagged in the chapter: a NIRS between-legs delta criterion whose stated direction is internally inconsistent, and a body-surface-area-to-cannula-size ratio quoted without units or derivation.
Incidence of limb ischaemia 10 to 70%, the spread attributed to differing populations, indications, cannulation techniques and DEFINITIONS. Cohort figures: 8.6% with surgical cutdown plus prophylactic distal perfusion; 12-33% despite a distal perfusion cannula; 14.7% in cardiogenic shock; 10.6% in ECPR. Fasciotomy 8.3% of one cardiogenic shock cohort and 7 of 34 (21%) of limb-ischaemia patients elsewhere; amputation 0.9% of one series and 3 of 34 (8.8%) of limb-ischaemia patients. Risk factors: cannulae above 20 Fr; lower incidence when the body-surface-area-to-cannula-size relationship exceeds 11; female sex; younger age (smaller femoral arteries and less collateral circulation); peripheral vascular disease; diabetes; respiratory disease; SOFA at cannulation; vasopressor use. Distal perfusion cannula 5-14 Fr, most commonly 6-8 Fr, into the proximal superficial femoral artery, wire placed at the time of the main femoral cannulation. Alternative routes: retrograde posterior tibial, contralateral femoral, end-to-side Dacron or Hemashield graft 6-8 mm. A 19 Fr bidirectional cannula with a 120-degree angled elbow gave adequate distal flow in 14 of 15 patients. MONITORING: clinical assessment several times per shift using the six Ps; Doppler ankle perfusion pressure under 50 mmHg indicates ischaemia; distal peak systolic velocity correlates POSITIVELY with pulse pressure and NEGATIVELY with ECMO pump flow; NIRS intervention thresholds rSO2 below 40 or a fall of more than 25% from baseline; all patients with clinical limb ischaemia had rSO2 below 50% for longer than 4 minutes, positive predictive value 86%. STAGING: loss of the arterial Doppler signal with the venous signal preserved indicates a threatened limb; absence of both signals indicates an irreversibly damaged, non-salvageable limb. CONSERVATIVE LADDER: reduce or discontinue vasopressors; optimise volume status and haemoglobin oxygen transport; optimise peripheral temperature; give a peripheral vasodilator through the distal perfusion cannula; maintain anticoagulation at the highest therapeutic level. INVASIVE: reposition the cannula (contralateral limb, subclavian or aortic), Fogarty embolectomy, arterial repair with suture or bovine pericardial patch, fasciotomy, amputation.
Adults on peripheral femoral VA ECMO. Critical Care 2019;23:266. Retrieved in full. FIRST AUTHOR DISPUTED: a bibliographic index returns Bonicolini; the retrieved citation line gave Lorusso. Same DOI, journal, year and content. No author list is asserted.